The Home NodeB (HNB) is a small-type and low-powered base station, deployed in indoor places such as home and office. The HNB is mainly used for providing users with higher service rate and reducing service costs required for enjoying high-speed service, meanwhile, compensating the overlap defect of current allocated cellular radio communication system. The HNB is featured with low-cost, convenience, low-power output and plug-and-play.
FIG. 1 is a schematic diagram of the structure of an HNB system. As shown in FIG. 1, an HNB user is connected to a core network via a Home NodeB Access Network (HNB AN), wherein the HNB AN is composed of a Home NodeB (HNB) and a Home NodeB Gateway (HNB GW), generally with a security gateway therebetween. The HNB GW is mainly functioned to verify security of the HNB, to process the registering of the HNB and an access control, and to exchange data between the core network and the HNB. A Home NodeB Management System (HMS) is used for managing the operation and maintenance of an HNB, for configuring and controlling the HNB according to the requirement of service providers, mainly for realizing the configuration and management function for the HNB, including the verification of location information and the parameter configuration for the HNB.
With the development of technology, the HNB is introduced with a concept of Close Subscriber Group (CSG), thus, the HNB can be classified into two types: a CSG supported NodeB and a CSG not-supported NodeB, meanwhile, user equipment (UE) can also be divided into two types: CSG supported UE and CSG not-supported UE, wherein the CSG supported UE can read CSG information from system broadcast and make an initial access judgment according to an Allowed CSG List of itself. The Allowed CSG List is a list of CSGs subscribed with a UE, and is saved in the UE and a core network (CN). Corresponding to the Allowed CSG List, the HNB GW preserves a list of IMSIs of UEs subscribed with the HNB, namely, the Allowed CSG List is a judgment basis for the CN to make an access control on a UE, and the IMSI list of UEs subscribed with the HNB is a judgment basis for the HNB GW to make an access control on a UE. Existing standards prescribe that, for a CSG not-supported UE or a CSG not-supported HNB, an access control on a UE is completed at the HNB-GW; and if both a UE and an HNB supports CSG function, an access control on the UE is completed at a CN.
FIG. 2 shows a flow chart of UE access in the case that a UE or an HNB does not support CSG function, As shown in FIG. 2, for a CSG not-supported UE or a CSG not-supported HNB, step 200-step 204 are implemented firstly: a UE establishes an is RRC connection with an HNB, during this process, the UE transmits its identifier (such as IMSI or TMSI), capability information and version information to the HNB; the UE transmits an RRC initial direct transmission message to the HNB, the message including an initial NAS message, such as Attach Request or Location Update (LU) Request or other NAS messages; the HNB checks whether the identifier of the UE is locally recorded, if there is no record of a Connect-ID allocated to the UE, then step 205 is executed, and if there is a record of a Connect-ID allocated to the UE, then registering is not needed; besides, prior to registering, the HNB may possibly trigger a flow of obtaining UE IMSI; the HNB optionally makes an access control via the IMSI of the UE, as well as it may performs an access control via local resources.
Then step 205-step 207 follow: the HNB transmits a UE register message to the HNB-GW, the HNB-GW judges whether to perform an access control on the UE according to the capability of the UE and an access reason. If an access control is needed to be performed, the HNB GW performs an access control on the UE according to the IMSI list of the UEs subscribed with the HNB. The UE whose IMSI is contained in the IMSI list or the UE who is making an emergency call is allowed access, and the UE is allocated with a Connect-ID as a signaling connection identifier, and it responds the HNB via a UE register accept message, otherwise, the HNB GW transmits a UE register reject message to the HNB. If Connect-ID information of the UE is preserved at the HNB locally, the access of the UE to a core network is carried out with taking the Connect-ID as a signaling connection identifier directly, without registering of the UE.
At last, step 208-step 211 follow: if the HNB accepts the access of the UE, then the HNB transmits a CONNECT message, wherein the CONNECT message includes an RANAP Initial UE message; upon receiving the CONNECT message, the HNB-GW forwards the Initial UE Message to the CN to trigger an SCCP establishment; the CN acknowledges the message for the SCCP connection; and the UE continues the NAS flow.
FIG. 3 shows a flow chart of UE access in the case that a UE and an HNB simultaneously support CSG function. As shown in FIG. 3, firstly, step 300-step 304 are: the UE and the HNB establish an RRC connection, during this process, the UE transmits is its identifier (e.g. IMSI or TMSI), capability information and version information to the HNB; the UE transmits an RRC initial direct transmission message to the HNB, the message including an initial NAS message, such as Attach Request or LU Request or other NAS messages; the HNB checks the capability of the UE, since the UE supports CSG function, the HNB transmits a UE register message to the HNB GW, and the HNB GW allows all access without an access control on the UE.
Then, step 305-step 309 follow: the HNB GW allocates a Connect-ID as a signaling connection identifier to the UE, and responds the HNB via a UE register accept message, if the HNB accepts the access of the UE, the HNB transmits a CONNECT message which includes an initial UE message; upon receiving the CONNECT message, the HNB-GW forwards the Initial UE Message to the CN to trigger an SCCP establishment; the CN acknowledges the message for the SCCP connection; optionally, a mobility management may be carried out between the UE and the CN, such as an authentication procedure.
At last, step 301-step 311 follow: after the CN performs an access control on the UE, the UE continues the NAS flow.
In addition, there are three access modes for a CSG cell: an Open Access Mode, a Close Access Mode and a Hybrid Access Mode, wherein, the CSG cell of Open Access Mode allows access of any user; the CSG cell of Close Access Mode only allows access of users subscribed with it, and rejects access of any non-subscriber; the CSG cell of Hybrid Access Mode accepts access of both subscribers and non-subscribers.
The access of subscribers is called access of members, as described herein, its actual access mode is Close; the access of non-subscribers is called Open access, wherein, the CSG cell of Hybrid Access Mode performs different QoS controls on users accessing with Close memberships and users accessing with Open memberships, further, in case of short resources, the HNB gives priority to the users accessing with Close memberships to enjoy service, and switches the users who access with Open memberships to a proper macro cell or HNB, or releases them directly, wherein the access mode of the HNB can be notified to the HNB-GW during the HNB registering process.
Thus, for an HNB running in Hybrid Access Mode, it is necessary to know the membership of a UE accessing to a CSG cell of Hybrid Access Mode. Subscription of CSG is related to users, namely the subscription is done with an IMSI. The CSG capability is a feature of a UE, which is relative to hardware and version, for instance the capability for reading system broadcast relative to CSG. Therefore, in actual application, there may exist such a case that for a UE which does not support CSG function (i.e. a non-CSG UE), its users may be registered as subscribers of a certain CSG, namely USIM/SIM of the subscribers is subscribed with the CSG, but software and hardware of the UE do not support functions of the CSG and are used on the UE which does not support the CSG, in this case if the UE accesses to an HNB belonging to the CSG subscribed with the UE, then the IMSI LIST of the HNB preserved in an HNB GW contains IMSI information of the UE. Since an access control on the UE is completed at the HNB GW, for a Hybrid CSG HNB, the specific access mode of the UE can only be known by the HNB-GW but the HNB, namely, according to current UE register flow, the HNB can not distinguish subscribers from non-subscribers. Thus, the HNB can not realize different QoS processing on services of different UEs, specially, in case of short resources, different QoS processing can not be carried out on services of different UEs according to UE access memberships.